Radiofrequency identification (RFID) tags are well known in the art. RFID tags are small electronic circuits that respond with a data-carrying RF reply signal when interrogated with an REF signal at a particular frequency. Tags are either passive or active. Passive tags rely on the energy of the interrogation signal to generate the reply signal; active tags carry their own battery. Active tags have a much longer range than active tags. Active tags typically can be queried at farther distances than passive tags. In recent years, the maximum range of both passive and active tags has been increased by technological advancements in the field.
A problem with REID tags is determining where the tag is located relative to the RFID reader device. Traditionally, locationing has been possible only with expensive RFID active tags that cost significantly more than passive tags, limiting passive tag applicability to tracking more expensive assets.
It is also a very challenging task to physically locate a passive tag by a reader or a set of readers. These challenges can be multifold. For example, in a warehouse environment, tags and readers may not be in the line of sight communication, thus communication between tags and readers can be diminished. In addition, the backscatter communication signals from tags can be weak and the backscattered messages short, further impacting effective communication between tags and readers.
Accordingly, there is a need for improved techniques and systems to effectively provide passive tag location information from among a RFID tag population.